Is it possible to vary the material color by location for a fluid?
Eureka! Thanks to Vince Scalia's suggestion of using a gradient node I figured it out and the results work perfectly. 

Now this was just for testing so it's a really simply case but you can see this material now simulates a light illuminating only the inflow. 

I'll show a picture of the node tree for clarification:

So the mapping nodes are for the coordinates of where we want the illumination to be. You need to have both the x-y location as well as a separate node for the height (z) of the inflow. Set the gradient texture node to spherical as well as your scale; a math node to combine each of them... input that into the factor of your mix shader with glass and an emission node and viola! Then you can add as many other lights as you want by just duplicating the entire node setup, changing your coordinates in the mapping node and adding another mix shader to combine them. Input all this data into the volume parameter of the material output. With this scheme you can now illuminate a fluid at any location any number of times with varying colors and best of all you can animate the whole thing with key frames!